WO2000047784A3 - Method for producing metallic silicon - Google Patents

Abstract

The present invention pertains to the metallurgy of non-ferrous metals and essentially relates to a carbo-thermal method for producing silicon used in the photo-electronic industry, mainly in the production of solar panels. This method improves the interphase interaction level between the silicon dioxide and a carbonated reducer obtained from an organic compound, which increases manufacturability, reduces the amount of energy for the SiO2 reduction process and increases the yield of the end product. The purpose of this invention is to produce silicon that can be used mainly in the production of solar panels, wherein said invention essentially relates to a method that involves carrying out a carbo-thermal reduction of silicon dioxide into silicon carbide using an organic reducer and reacting the silicon carbide with the silicon dioxide. The starting material consists of silicon dioxide having a predetermined purity level, while the organic reducer consists of a carbon-containing reducer based on liquid phenolic resins and having a predetermined purity level. The method for producing silicon itself includes three techniques of thermal processing starting from room temperatures of up to 160° C at 0.1-0.7 MPa, of up to 800° C in an inert medium and of up to 1700° C in an inert gas medium. The method further involves reaching in two steps a temperature of 1300-1400° C at 0.01 Pa and, from there, a temperature of up to 1800° C at a variable pressure of 0.01 Pa to 0.1 MPa. The silicon dioxide has an impurity content not exceeding 190 ppm, while the carbon-containing reducer based on liquid phenolic resins has an impurity content not exceeding 80 ppm.